An issue was discovered in Xen through 4.13.x, allowing guest OS users to cause a host OS crash because of incorrect error handling in event-channel port allocation. The allocation of an event-channel port may fail for multiple reasons: (1) port is already in use, (2) the memory allocation failed, or (3) the port we try to allocate is higher than what is supported by the ABI (e.g., 2L or FIFO) used by the guest or the limit set by an administrator (max_event_channels in xl cfg). Due to the missing error checks, only (1) will be considered an error. All the other cases will provide a valid port and will result in a crash when trying to access the event channel. When the administrator configured a guest to allow more than 1023 event channels, that guest may be able to crash the host. When Xen is out-of-memory, allocation of new event channels will result in crashing the host rather than reporting an error. Xen versions 4.10 and later are affected. All architectures are affected. The default configuration, when guests are created with xl/libxl, is not vulnerable, because of the default event-channel limit.
CVE-2020-15566
“—” beside the score: it is equal to NVD's CVSS score.
Score 6.5 from GitHub Security Advisory published 2022-05-24. NVD baseline CVSS 6.5; sources differ by 0.0.
Also known asEUVD-2020-7553 (ENISA EUVD) · GHSA-2v7g-8jvx-2wfc (GitHub Security Advisories)Source: ENISA EUVD
- Lower severity and no public exploit yet
A fix is available — apply it.
- CVSS v3
- 6.5
- EG Score
- 6.5MEDIUMmedium confidence
- EG Risk
- 29EG Risk 29/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity65% × 45%Impact severity (EG Severity): CVSS 6.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation0.4% × 40%FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.Automatability0% × 15%CISA's BOD 26-04 default: no one has published Automatable for this CVE, and CISA treats it as “no” for a CVE not in KEV.SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: A fix is available. Apply it within your standard update timelines. - EPSS PROB
- 0.4%
- EPSS %ILE
- 35th
- KEV
- Not listed
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (6.5): severity, escalated by confirmed exploitation. This CVE's 6.5 is its impact severity (EG Severity), not escalated.
- EG Severity
- 6.5 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.4% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-25). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines.
Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
July 7, 2020
Last Modified
November 21, 2024
References (8)
- MITRE · CVE Programhttp://lists.opensuse.org/opensuse-security-announce/2020-07/msg00024.html
- MITRE · CVE Programhttp://lists.opensuse.org/opensuse-security-announce/2020-07/msg00031.html
- MITRE · CVE Programhttp://www.openwall.com/lists/oss-security/2020/07/07/2Mailing List · Third Party Advisory
- MITRE · CVE Programhttp://xenbits.xen.org/xsa/advisory-317.htmlVendor Advisory
- MITRE · CVE Programhttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MXESCOVI7AVRNC7HEAMFM7PMEO6D3AUH/
- MITRE · CVE Programhttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VB3QJJZV23Z2IDYEMIHELWYSQBUEW6JP/
- MITRE · CVE Programhttps://security.gentoo.org/glsa/202007-02
- MITRE · CVE Programhttps://www.debian.org/security/2020/dsa-4723Third Party Advisory
Patch Availability(1)
| Vendor / Ecosystem | Fix (by version range) / Patch | Released | Source |
|---|---|---|---|
| ubuntu | xen-system-armhf (4.11.3+24-g14b62ab3e5-1ubuntu2.3) @ focal | 2026-10-25 | ubuntu |
Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.
Affected Packages
(21 across 21 ecosystems)
Alpine:v3.10(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| xen | — |
| — |
Alpine:v3.11(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| xen | — |
| — |
Alpine:v3.12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| xen | — |
| — |
Alpine:v3.13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| xen | — |
| — |
Alpine:v3.14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| xen | — |
| — |
Alpine:v3.15(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| xen | — |
| — |
Alpine:v3.16(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| xen | — |
| — |
Alpine:v3.17(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| xen | — |
| — |
Alpine:v3.18(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| xen | — |
| — |
Alpine:v3.19(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| xen | — |
| — |
Alpine:v3.20(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| xen | — |
| — |
Alpine:v3.21(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| xen | — |
| — |
Alpine:v3.22(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| xen | — |
| — |
Alpine:v3.23(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| xen | — |
| — |
Alpine:v3.24(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| xen | — |
| — |
Alpine:v3.9(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| xen | — |
| — |
Debian:10(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| xen | 4.11.1+92-g6c33308a8d-2, 4.11.3+24-g14b62ab3e5-1, 4.11.3+24-g14b62ab3e5-1~deb10u1, 4.11.4-1 |
| — |
Debian:11(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| xen | — |
| — |
Debian:12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| xen | — |
| — |
Debian:13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| xen | — |
| — |
Debian:14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| xen | — |
| — |
Weakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
All Vendor Advisories
(1)
Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.
Data Freshness Timeline
(refreshed 7× in last 7d / 38× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
Showing the most recent 97 of 200 refreshes on record for this CVE.
A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 3 repeat rows among the latest 100 are merged into the row they repeat. The 103 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-11-01 16:29 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-10-31 16:28 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-10-30 16:29 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-10-29 16:28 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-10-28 16:27 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-10-27 16:27 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-26 16:27 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-25 18:49 UTCEG score recompute
- 2026-10-25 16:28 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-25 02:29 UTCEG score recompute
- 2026-10-25 02:29 UTCVendor advisory
- 2026-10-25 02:29 UTCGHSA enrichmentGHSA-2v7g-8jvx-2wfc · GitHub CVSS 6.5
- 2026-10-24 16:28 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-23 16:27 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-22 16:29 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-21 16:28 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-20 16:28 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-19 16:27 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-19 15:55 UTCOSV refresh
- 2026-10-18 16:28 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-18 09:33 UTCEG score recompute
- 2026-10-17 16:28 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-16 16:33 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-15 16:27 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-14 16:28 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
Show 72 moreShow fewer
- 2026-10-13 16:28 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-12 19:44 UTCEG score recompute
- 2026-10-12 16:29 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-12 00:07 UTCEG score recompute
- 2026-10-11 13:43 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-10 19:56 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-09 20:04 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-08 16:38 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-07 23:44 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-06 15:13 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
- 2026-10-05 17:39 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
- 2026-10-04 23:18 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
- 2026-10-03 14:22 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
- 2026-10-02 16:22 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
- 2026-09-30 15:12 UTCEG score recompute
- 2026-09-30 14:59 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
- 2026-09-27 13:40 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
- 2026-09-26 21:42 UTCOSV refresh
- 2026-09-26 15:54 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
- 2026-09-26 00:20 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
- 2026-09-24 14:00 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
- 2026-09-22 14:43 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-21 20:28 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-20 20:11 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-18 19:23 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-17 19:22 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-16 14:04 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-15 03:06 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-13 16:42 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-12 14:56 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-11 14:48 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-11 09:32 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-10 09:29 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-08 21:56 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-07 15:57 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-07 07:18 UTCOSV refresh
- 2026-09-06 13:44 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-05 15:24 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-04 13:57 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-04 05:03 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-02 14:08 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-01 03:32 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-30 19:14 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-30 01:18 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-27 14:21 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-26 14:42 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-25 13:45 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-21 23:45 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-20 22:52 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-20 17:01 UTCOSV refresh
- 2026-08-19 17:00 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-18 13:44 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-17 13:43 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-16 14:52 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-16 02:11 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-15 01:26 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-13 21:57 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-12 13:47 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-09 13:43 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-08 16:33 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-07 16:23 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-06 13:43 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-05 19:14 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-05 10:41 UTCOSV refresh
- 2026-08-04 15:06 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-04 10:34 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-03 10:32 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-02 02:23 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-01 04:12 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-07-30 16:25 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-07-30 01:27 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-07-28 15:32 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
Related CVEs(same product + same vendor + same CWE)
Same product
10 shownDebian:10:xen
Same vendor
10 shownubuntu:USN-5617-1
Frequently asked(5)
What is CVE-2020-15566?
When was the CVE record for CVE-2020-15566 published?
Is CVE-2020-15566 actively exploited?
What is the CVSS score of CVE-2020-15566?
How do I remediate CVE-2020-15566?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2020-15566
Is Your Infrastructure Affected by CVE-2020-15566?
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